Flavonoids, or bioflavonoids, are a ubiquitous group of polyphenolic substances which are present in most plants, concentrating in seeds, fruit skin or peel, bark, and flowers. A great number of plant medicines contain flavonoids, which have been reported by many authors as having antibacterial, antioxidant, anti-inflammatory, antiallergic, antimutagenic, antiviral, antineoplastic, anti-thrombotic, and vasodilatory actions.
Recent developments described in WO 2005/058255 A1 also show the benefits of flavanone-containing compositions for improving the skin, hair and coat health of humans or pets.
In nature, these compounds mainly occur as glycosides. This conjugation with sugars impacts markedly their kinetics of absorption. For instance, flavonoid glucosides have a fast and early absorption while flavonoid rutinosides (rhamnose-glucoside) have a slow and late absorption.
For flavonoid rutinosides such as hesperidin, bioavailability is low and late in mammals due to the lack of the enzyme α-rhamnosidase in the small intestine, which would remove the rhamnose moiety of said flavonoid rutinosides. This leads to time-consuming progression of flavonoid rutinosides in the gastro-intestinal tract through to the colon.
Health foods and drinks containing long-acting flavonoid glycosides are described in JP 2003-073279 whereby a mixture of flavonoids having various degrees of glycosylation is included in the food product such that the absorption occurs throughout the gastro-intestinal tract.
JP 2000-078955 also describes a way to improve the absorption of flavonoids in food or medicine by providing a mixture of physiologically active flavonoids and derivatives thereof.
Further, Espin J. C. et al. describe in the Journal of Agricultural and Food Chemistry, 2004, 52(20), p. 6136-6142, the production of bioavailable glucoside flavonoids in fruit juices and green tea. This is achieved by treating the fruit juices and green tea with rhamnosidase enzymes from Aspergillus aculeatus. 